超细TiC0.7N0.3基金属陶瓷的切削性能研究

采用超细TiC0 7N0 3 粉制备了超细金属陶瓷刀片。该刀片加工 9CrSi调质钢时 ,寿命比普通金属陶瓷刀片提高 2～ 3倍 ,切削力小 ,切削轻快 ,被加工表面质量显著提高。讨论了该刀片切削性能改善的机理。     

聚烯烃超细纤维的制备技术

聚烯烃超细纤维特有的结构与性能使其研究与生产技术发展迅速,生产量也在飞速地增长。本文综述了聚烯烃超细纤维的制备技术,详细介绍了直接纺丝法、复合纺丝法、高压静电纺丝法、熔喷非织造技术、模板合成法等聚烯烃超细纤维制备方法。迄今为止,国内及国际对于超细纤维的概念并没有公认的定义,一般认为单纤维线密度为0．1～1．0dtex的纤维属于超细纤维,而线密度〈0．1 dtex的纤维一般称为极细纤维。     

异相电解/超声波方法制备超细金属粉末

研究一种异相电解/超声波制备超细金属粉末的新方法,并应用该方法对制备超细铁粉末进行研究,成功地制备出超细金属铁粉末。该方法主要用于相对氢而言的较活泼金属粉末的制备,也可以应用于相对氢而言的不活泼金属粉末的制备,适用范围广,电解效率高,成本低,具有工业化应用前景。     

世界粉末冶金新进展

从微细和超细粉末制备、粉末冶金新工艺和粉末新材料两方面简述世界粉末冶金科技的进展和动向。     

超细碳化钨粉末掺量对合金刀头相结构和力学性能的影响

采用超细WC粉末、工业级的Sn、Ni、Co、Cu粉末和金刚石为原料,经真空烧结后制备成合金刀头。用XRD测试了WC粉末和合金的相结构,用SEM观察了WC粉末和合金的形貌。研究结果表明,超细WC的添加能改善以Sn-Ni-Co-Cu结合的金刚石合金刀头的力学性能,最终可获得HRB101和1180MPa的材料。     

热压烧结制备高密度钨铜合金

以用机械合金化法制备的超细W-15Cu复合粉末为原料,采用热压烧结工艺制备了高密度的W-15Cu合金,用扫描电镜、硬度仪、密度测试仪等研究了烧结工艺对合金组织和性能的影响.结果表明:采用高能球磨可以制备出钨晶粒镶嵌铜相中的复合粉末;采用热压烧结,在30MPa、1 500 ℃×2 h的条件下,可以制备出相对密度99.8%、断裂强度1290.6 MPa、硬度44.8HRC的高密度钨铜合金.     

片状超细WS_2粉末的制备及其润滑性能研究

当WS2粉末的基面与材料表面平行时,润滑效果最好,因此纳米片状形貌能极大地改善WS2粉末的润滑效果。为制备纳米片状WS2粉末,将分析纯WO3和S粉末在氩气保护下进行球磨,将球磨后的混合粉末在硫蒸气气氛中进行硫化得到WS2粉末。基于XRD和SEM的成分和形貌分析表明,通过球磨加硫化的方法成功制备出边缘长度在250~500 nm,厚度小于100 nm的片状超细WS2粉末。将片状超细WS2粉末添加到石蜡油中进行标准四球摩擦试验,结果表明:该粉末可显著提高石蜡油最大无卡咬负荷值,同时有效减小磨斑直径,其中质量分数1.3%的片状超细WS2粉末可使石蜡油的最大无卡咬负荷值增加118 N,质量分数1.5%的片状超细WS2粉末可使试样的平均磨斑直径减小0.33 mm。     

激光气相法制造超细粉末的研究

本文论述了激光气相法制造超细粉末的原理及其制粉装置的结构设计。研究了Si_3N_4SiC、B_4C、Si-C-B、Si等5种超细粉末的制造工艺条件及粉体表征特性,并结合制出的粉体性能对气相法的特点进行了讨论。     

Ni-TiC复合镀工艺的优化

采用共沉积法(CECD),在不锈钢上制备Ni TiC复合镀层。主要研究了TiC粒子的浓度、阴极电流密度、pH值等 对复合镀层中粒子含量的影响。利用正交试验法优选出制备Ni TiC复合镀层的最佳工艺参数。结果表明,Ni TiC复合 镀层的最佳工艺参数为:TiC粒子的浓度6g/L,电流密度4A/dm2,pH=4,镀液温度30℃。     

N80油管内壁激光原位合成TiC-Ni涂层组织研究

在N80油管内壁通过激光合金化Ni-Cr-Ti-C粉末制备出合金化涂层,采用XRD、EPMA、TEM对涂层进行分析.结果表明:合金化层由(Fe,Cr,Ni)-奥氏体、(Fe,Ni)-奥氏体及原位合成的TiC颗粒等组成,合金化层的组织晶粒细小致密;TiC/Ni界面存在如下位向关系:(001)TiC//(111)γ-Ni,TiC颗粒中存在呈一定方向分布的位错,γ-Ni相内部的位错杂乱分布。     

Eddy-current testing of fatigue degradation under contact loading of NiCrBSi coatings obtained through gas–powder laser cladding

The possibilities of using the eddy-current method for testing the fatigue degradation under contact loading of NiCrBSi coatings were investigated. These coatings are obtained using the method of the gas–powder laser cladding from powders with different contents of chromium, boron, carbon, and additives of titanium carbide TiC (15 and 25 wt. %). It was established that eddy-current testing of fatigue degradation under contact loading of PG-SR2 and PG-10N-01 coatings can be performed at high excitation frequencies of an eddy-current transducer, when the depth of the analyzed layer is maximally close to the thickness of the surface layer that was subjected to fatigue degradation. Testing the fatigue degradation under contact loading of TiC–PG-SR2 composite coatings with TiC-additive contents of 15 and 25 wt. % has certain limitations and features that result from the presence of a significant number of discontinuity flaws in the structure of these coatings.     

热压条件下金刚石微粉的石墨化相变行为及对陶瓷断裂韧性的影响

研究了金刚石微粉在热压条件下的石墨化相变行为及对陶瓷材料断裂韧性的影响;初步认为在Al2O3/TiC陶瓷材料中适量添加金刚石微粉,能显著提高材料的断裂韧性,在该试验条件下,所添加的金刚石微粉已全部石墨化,由于热残余应力的作用,在氧化铝/石墨和碳化钛/石墨界面上有裂纹形成,但界面附近没有观察到明显的化学反应。     

TiC的新型制备方法

自蔓延法和机械合金化法已被广泛地应用于制备新材料.介绍了自蔓延法和机械合金化法及其诱导自蔓延法制备TiC的过程和影响因素.     

打壳锤头等离子堆焊镍基涂层组织和性能

采用等离子堆焊技术在打壳锤头基体Q235钢表面进行堆焊,堆焊材料选用分别含有50%WC、40%WC和30%WC+TiC的复合镍基粉末。借助金相显微镜、扫描电子显微镜、显微硬度仪、摩擦磨损试验仪等仪器对所得各堆焊层的显微组织、化学成分、显微硬度、耐磨性和耐蚀性进行分析。试验结果表明,三种合金堆焊层显微组织均为γ-Ni固溶体和弥散分布的不同形态的硬质化合物相,如WC,(Ti,V)C等。三种合金堆焊层与基体界面处冶金结合良好,堆焊层稀释率低,且与基体Q235钢相比,耐电解腐蚀性显著提高。含有30%WC+TiC的镍基合金堆焊层与含有50%WC和40%WC的镍基合金堆焊层相比,具有更高的耐磨性和抗热腐蚀性。因而含有30%WC+TiC的镍基合金堆焊层综合性能最优,能够大幅度延长打壳锤头使用寿命,具有广泛的应用前景。     

机械合金化法制备Finemet非晶粉体的研究

利用高能卧式搅拌球磨机,研究了利用机械合金化法制备Finemet非晶粉体的工艺,研究结果表明,通过高速球磨可以得到部分非晶粉体。非晶化机制是局域熔体的快速冷却,粉体结块和粘壁,是机械合金化法制备高纯度Finemet非晶粉体的主要阻碍因素。     

Microstructure and wear properties of in situ TiC/FeCrBSi composite coating prepared by gas tungsten arc welding

Using a gas tungsten arc welding (GTAW) process, in situ synthesis TiC particles reinforced Fe-based alloy composite coating has been produced by preplaced FeCrBSi alloy, graphite and ferrotitanium powders. The microstructure and wear properties of the composite coatings were studied by means of scanning electron microscopy (SEM), X-ray diffractometer (XRD) and wear test. The effects of thickness of the pre-placed powder layer on the microstructure, hardness and wear resistance of the composite coatings were also investigated. The results indicated that TiC particles were produced by direct metallurgical reaction between ferrotitanium and graphite during the GTAW process. TiC particles with sizes in the range of 3–5 μm were dispersed in the matrix. The volume fraction of TiC particles and microhardness gradually increased from the bottom to the top of the composite coatings. The TiC-reinforced composite coatings enhance the hardness and wear resistance. The highest wear resistance of the composite coating with a 1.2 mm layer was obtained.     

Microstructure and wear properties of in situ TiC/FeCrBSi composite coating prepared by gas tungsten arc welding

Using a gas tungsten arc welding (GTAW) process, in situ synthesis TiC particles reinforced Fe-based alloy composite coating has been produced by pre-coated FeCrBSi alloy, graphite and ferrotitanium powders on the substrate. The microstructure and wear properties of the composite coatings were studied by means of scanning electron microscopy (SEM), X-ray diffractometer (XRD) and wear test. The effects of thickness of the pre-coated powder layer on the microstructure, hardness and wear resistance of the composite coatings were also investigated. The results indicated that TiC particles were produced by direct metallurgical reaction between ferrotitanium and graphite during the GTAW process. TiC particles with sizes in the range of 3–5 μm were dispersed in the matrix. The volume fraction of TiC particles and microhardness gradually increased from the bottom to the top of the composite coatings. The TiC-reinforced composite coatings enhance the hardness and wear resistance. The highest wear resistance of the composite coating with a 1.2 mm layer was obtained.     

C/C复合材料热防护涂层残余应力研究

对在C／C复合材料基体上制备的W-TiC梯度功能涂层过程中的残余热应力进行了计算机有限元模拟；并模拟了单-W和单-TiC涂层下的残余热应力分布情况，模拟结果表明，W-TiC的梯度功能涂层与单一涂层相比，具有更好的热应力缓和特性。在综合考虑热应力最小，应力强度比值最小以及纯TiC侧应力状态等因素的基础上，完成了功能梯度涂层体系的热应力缓和特性设计，得到组成分布指数P=1．5的最佳设计结果。     

电沉积稀土改性陶瓷涂层磨损性能研究

探讨了在电火花加工机床上沉积碳化钛金属陶瓷涂层方法,利用TiC,WC,Mo,N i粉未添加不同比例稀土元素在高压下压制并烧结了试验电极,在45#钢表面沉积了不同稀土含量的TiC陶瓷涂层,并用扫描电镜(SEM)、X射线衍射仪(XRD)、显微硬度计、环块式磨损试验机对涂层组成、组织形态进行、硬度及摩擦学性能分别进行了研究,并结合试验结果进行了理论分析。试验结果表明:用电火花放电法可沉积TiC陶瓷涂层,涂层中加入质量分数为0.5%的氧化镧后,涂层的耐磨性能较未加稀土涂层提高了3倍,摩擦因数减少10%,而加入过多的稀土镧氧化物则不利于涂层组织性能及耐磨性能的改善。稀土氧化镧对涂层的组织有改善作用,加入适量的稀土元素使得涂层致密性提高,减少涂层中的缺陷,涂层表面呈多孔结构特性。